RNA 3'-terminal phosphate cyclase catalyzes the ATP-dependent conversion of the 3'-phosphate to a 2',3'-cyclic phosphodiester at the end of RNA. It is an essential enzyme and conserved across all kingdoms. Data were collected for a crystal of RNA 3' Phosphate cyclase soaked in the solution containing 10mM AMP. Data collection statistics: 97% completeness at 3 A resolution and the R-factor (20 A - 3A) is 5.7. Unfortunately, it does not appear that AMP was bound with detectable occupancy.